1. Field of the Invention
The present invention relates to an internal-combustion-engine ignition diagnosis apparatus that diagnoses the condition of a spark discharge generated by an ignition device and to an internal-combustion-engine control apparatus provided with the ignition diagnosis apparatus.
2. Description of the Related Art
In recent years, problems of environmental conservation and fuel depletion have been raised, and also in the automobile industry, solutions to these problems have become big issues.
As solutions to the foregoing problems, many technologies that intend to raise the efficiency of an engine as much as possible have been developed; some of them utilize an exhaust gas recirculation method (referred to as “EGR”, hereinafter) in order to reduce an intake loss.
In the EGR method, an exhaust gas, which is a burned material, is introduced again into a combustion chamber; in particular, because, in the case where a great deal of exhaust gas is utilized, nonflammable burned materials much affect the combustion, the combustion temperature decreases and the combustion flame does not readily spread, whereby combustibility is deteriorated; therefore, an internal combustion engine utilizing a so-called multi-point ignition system, which ensures combustibility by utilizing a plurality of ignition plugs in the same combustion chamber of an internal combustion engine, has been proposed and realized.
However, in the case of a multi-point ignition system, because, even when part of the ignition systems fail, combustion can be continued in many cases, no malfunction of this kind can be detected by an existing misfire detection system. Accordingly, because required ignition energy cannot be obtained, deterioration in an exhaust gas (an emission) due to deterioration in the combustion condition and deterioration in the gasoline mileage due to output decrease are caused, whereby a disadvantage occurs, despite the realization of environmental conservation.
In addition, as an apparatus that performs a failure diagnosis on an ignition coil, an apparatus is disclosed in which a primary current flowing through the primary coil of an ignition coil is detected and a failure diagnosis is performed based on whether or not the primary current flows (e.g., refer to Japanese Patent No. 3614150)
The conventional apparatus disclosed in Japanese Patent No. 3614150 is nothing but an apparatus in which an input signal for activating the ignition coil is inputted, and based on the input signal, it is ascertained whether or not the operation of the primary coil of the ignition coil has been performed; thus, it is not required to ascertain whether or not a spark has eventually been discharged. For example, in a failure mode such as a short circuit across the secondary coil of the ignition coil or a short circuit between the electrodes of an ignition plug, no-spark operation cannot be detected; therefore, it has been a problem that deterioration in the gasoline mileage and deterioration in the emission caused in the foregoing failure mode cannot be recognized.